Near infrared spectroscopy (NIRS) is used for a wide variety of applications due to its noninvasiveness, ease of use, quick acquisition time, and affordability. In this study we investigate the effectiveness of spatial frequency domain imaging (SFDI), a widefield noncontact quantitative NIRS technique, to assess peripheral artery disease progression in vivo. SFDI measures absolute (i.e. optical scattering-corrected) tissue concentrations of oxy- hemoglobin and deoxyhemoglobin, and therefore total hemoglobin concentration and tissue oxygen saturation. Female apolipoprotein E-deficient mice (n=9) underwent femoral artery ligation to induce unilateral ischemia in the left hindlimb. Brie y, the left femoral artery was exposed and ligated via suture midway between the aortic trifurcation and division into the saphenous and popliteal arteries. SFDI was acquired for both the ischemic and control limbs over 4 weeks to track changes in vascular perfusion. We also acquired high frequency pulsed-wave Doppler ultrasound images and performed histological analysis, both of which confirmed occlusion of the left femoral artery post-ligation. The ischemic to control ratio for tissue oxygen saturation was 0.96±0.06 at baseline and 0.86±0.10 at day 1, 0.94±0.06 at day 3, 0.95±0.14 at day 7, 0.91±0.09 at day 14, 0.90±0.09 at day 21, and 1.01±0.09 at day 28. These results demonstrate the ability of NIRS to detect a decrease in tissue oxygen saturation in the ischemic limb within a week of ischemic injury, followed by recovery at 4 weeks post-ligation. Our work provides evidence for the potential of SFDI to accurately and noninvasively quantify peripheral artery disease progression in a preclinical murine model.
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